Hi
Although, not specifically an operating system, Forth
can be used as an operating system. The normal disk
I/O can be easily expanded to include file systems.
Many tools for all kinds of things have been done
in Forth. Examples: editors, assemblers, compilers,
spread sheets, etc. If you have an old system with
no OS, Forth is always an option. Implementing Forth
on a machine is one of the few things I've always
felt was something that didn't take a company staff
to do. Once the basic core was implemented, one
could expand it to whatever one wanted. I've done
several over the years.
Dwight